Telephone system



L. J. "BOWNE TELEPHONE SYSTEM 7 June 10 1924.

Filed May, 29 192? I'H" y LANGFORD J, BOWNE, OF HOWARD BEACH, NEW YORK, ASSIGNOB TO WESTERN ELEO TRIO COMPANY, INCORPORATED, 013 NEW YORK, N. Y., A CORPORATION OF NEW YORK. a

TELEPHONE SYSTEM.

Application filed May 29, 1922.

To all whom it may concern:

Be it known that I, LANGF'ORD J. BOWNE, a citizen of the United States, residing at Howard Beach, in the county of Queens, State of New York, have invented certain new and useful Improvements in Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone systerns, and particularly to signaling over telephone circuits used in connection with transmissionlines composited for simultaneous telephony and telegraphy.

In establishing connections between a toll line and a subscribers station, a cord circuit at a toll operators position and a toll switching trunk extending from the operators position to a B operators position at an office in which the calling or called subscribers station is located are usually employed. To enable the toll operator to fully supervise the connection, the cord circuit is provided with a supervisory signal to indicate when the subscriber answers, hangs up or flashes. Toll lines extending from one city to another are quite often composited so that telephone conversations and telegraph messages may be transmitted over the toll line at the same time. It has been found in practice that when the subscriber flashes to attract the attention of the toll operator, impulses are produced in the toll line which may aflect the composite apparatus therein so as to cause false operation thereof. 1

An object of this invention is, therefore, to prevent in a system of this nature false operation of apparatus in the composite circuit when the subscriber flashes. 1

To attain the object of this invention the toll switching, trunk, having two sections inductively coupled for the purpose of feeding talking and signaling battery over the ends thereof, is provided with means which is actuated during the flashing period to render the inductive device ineffective to produce false signals in the composited circuit during the flashing period.

Referring to the drawings, there is shown a subscribers station A, a toll switching trunk T, and such parts of toll cord circuits C and C and a composited toll line L as are necessary for an understanding of the invention. The subscribers station A is connected to a jack 1 located at the B operators position. The toll switching trunk T is Serial No. 564,329.

shown as terminating in a plug'2 at the trunk operators position and in a jack 14 at the toll o-perators position. The repeating coil 9 inductively divides the trunk circuit T into two sections. Talking'and signaling current for the subscriber at station A is fed through one winding of the repeating coil and signaling current for operating the supervisory apparatus in the'cord circuit C is fed through the other winding of the repeating coil. To insure good transmission over toll lines it is customary although not absolutely necessary, to connect a higher voltage battery to the plug 2 than is connected to the jack 14. Associated with the cord circuit' C is a supervisory lamp 18 which serves to indicate when the subscriber at station A answers, hangs up and flashes. At one end of the toll line L a rectangle R is shown to indicate that composite equipment is connected with that end ofthe toll line which is a duplicate of that shown between the drop 58 and conductors 81 and 82.

Certain of the relays are of the slow-to actuate type and for the purpose of indicating this on the drawing, arrows," pointing in the direction in which the armatures slowly move, are shown. I

It is believed that a clearer unders'tand ing of the invention may be had from a detailed description of the operation. Assuming first that a call is incoming over the toll line L, 135 cycle current under the control of the operator at the distant end of the toll line will cause the operation of relay 68 over a path extending from source of 135 cycle current corresponding to the source 65, conductor 81, upper normal contacts of relay 64:, right-hand winding of retardation coil 78, condenser 74:, winding of relay 68, lower normal contacts of relay 64, conductor 82, to source of 185cyclecu rrent at the distant end of the toll line. Relay 68 thereupon operates andcauses the release of the normally operated relay66. Relay #66, in releasing. causes the operation of relay 72 over an obvious circuit. Relay 72, in operating, connects16 cycle current from the source 190 to the'drop 58. As long as the current from 'the 135 cycle source is applied to the conductors 81 and 82, relays 68 and 72 will be operated. As soon as current is removed from the conductors 81 and 82, relays 68 and 72 restore to normal. The actuation of the drop 58 indicates to the operator that a call has arrived whereupon she inserts plug 23 into jack 24C of the toll line L and then actuates a listening key (not shown) to ascertain the number of the subscriber desired, whereupon the operator restores the listening key (not shown) to normal. Assuming that the subscriber at station A is desired the operator will actuate a call wire key (not shown) to place her telephone set in circuit with the operators telephone set (not shown) at the trunk position. The operator at the trunk position will then assign a trunk circuit and insert the plug 2 into the jack 1 of the desired line. Upon receiving the assignment of the trunk the tolloperator restores the call wire key (not shown) to normal and inserts the plug 15into the jack 14- of the assigned trunk.

Insertion of the plug 2 into the jack 1 causes'the energization of relays 3 and 6 over a path extending from ground through the winding of relay 3, sleeves of jack 1 and plug 2 and winding of relay 6 to grounded battery. Relay 3, in operating, disconnects the line relay t from the station A. Relay 6, in operating, disconnects the test lead 10 from the operators telephoneset (not shown) and renders the tip talking. conductor of the trunk circuit continuous. Relay 6, in operating, also causes the operation of slow-to-release relay 13 over a path extending from ground through the lowermost contacts of relay 6, outer righthand armature and back contact of relay 22., and winding of relay 13 to grounded battery. The operation of relay 13 at this time performs no useful function. It the operator at the B position inserts plug 2 into the jack 1 before the operator at the toll position inserts plug 15 into the jack 14, guard and supervisory lamp 7 will light over a path extending from grounded battery through lamp 7 lower inner alternate contacts of relay 6 and back contact and left-hand armature of relay 12 to ground.

When the toll. operator inserts the plug 15 into the jack 14 relay 12 energizes over a circuit extending from ground through the left-hand winding of relay 12, contacts 50 and 51 of relay 13, tips of jack 1 1 and plug 15, upper normal contacts of key 1.9, winding of relay 16, lower normal contacts of key 19, rings of plug 15 and jack 14, contacts 52 of relay 13, inner right-hand normal contacts of relay 22 and right-hand winding of relay 12. to grounded battery. Relay 12, in operating, opens the circuit "for lamp 7 causing it to be extinguished, thereby indicating to the operator at the B position that the trunk assigned has been taken by the toll operator. Relay 16. in operating; closes an oby'ious circuit for lamp 18 and causes said lamp to light. The toll operator will then actuate the ringing key 19 tor the purpose of signaling the desired station A, whereupon 16 cycle ringing current is propagated over the cord andtrunk circuit over a path extending from ground through the upper alternate contacts of key 19, tips of plug 15 and jack 1 contacts 51 of relay 13, winding of alternate current relay 11, condenser 21, contacts 52 of relay 13, rings of jack 14: and plug 15, and lower alternate contacts of key 19 to source of ringing current 20. Relay 11, in operating, closes a circuit for relays 8 and 22 over a path extending from ground through the armature and front contact 01' relay 11, winding oi relay 8, and right-hand winding of relay 22 to grounded battery. Relay 8 operates in this circuit and connects 16 cycle ringing current from the source 57 to the talking conductors of the cord circuit which causes the bell 53 at the called station A to ring, as long as the ringing key 19 is actuated. Relay 22, in operating, opens the circuit for slow-torelease relay 13, which relay, in releasing, removes the short-circuit from the right hand windings of the repeating coil. Relay 22, in operating, also opens the previously traced energizing circuit for relay 12 but a circuit for maintaining said relay 12 operated is closed through the make-before-break contacts of relay 22. As soon as the toll operator ceases ringing, relays 11, 8 and 22 release and re lay 13 again operates.

When the subscriber at station A removes the receiver from the switchhook, relay 10 operates over a circuit extending from ground through the upper left-hand winding of repeating coil 9, upper normal contacts of relay 8, upper alternate contacts of relay 6, tips of plug 2 and jack 1 through the loop of station A, rings of jack 1 and plug 2. lower normal contacts of relay 8, lower left-hand winding of repeating coil 9, and winding of relay 10 to grounded battery. Relay 10, in operating, completes a circuit for relay 22 over a path extending from grounded battery through the righthand winding of relay 22, front contact and left-hand armature of relay 1(), left-hand winding of relay 22, and front contact and left-hand armature of relay 12 to ground. Relay 22 operates in this circuit and in opening its inner right-hand normal contacts removes grounded battery from the talking conductors of the cord circuit C causing the deenergization of relay 16 and the extinguishment of supervisory lamp 18. WVhen relay 22 is operated ground at inner alternate contacts of relay 22 is connected to the right-hand winding of relay 12 to maintain said relay 12 operated. Relay 22, in operating. also opens. at its outer righthand contacts, the circuit for the slow-torelease relay 13. Relay 13 being of the slow-to-release type retracts its armatures shortly after relay 22 operates. Relay 13,

in releasing, removes the short-circuit from the righthand windings of the repeating coil 9. i

The circuit is now in condition for talking and if, before finally hanging up the receiver, the subscriber at station A, for any reason, desires to attract the attention. of the toll operator, he may repeatedly move the switchhook 54 up and down causing the release and energization of relay 10. Relay 22 releases each time relay 1O releases due to the opening of the left-hand contacts of relay 10. Each time relay 22 releases battery is connected to the trunk and cord circuit and to the winding of relay 16 through the winding of relay 12 causing the energization and consequent lighting of lamp 18. The alternate interruptions and closures of the line at the station A thus cause the lamp 18 to be flashed. Slow-torelease relay 13 operates over its original energizing circuit at the beginning of the flashing period and remains operated during the flashing period. Belay 13, in operating, short-circuits the right-hand windings of repeating coil 9, thereby preventing impulses induced in the secondary of the coil from passing on to the apparatus in the composited line. The circuit for relay 6() of the composited circuit is made resonant to 16 cycle and that for relay 68 is made resonant to 135 cycle current and it has been found that where the subscribers lines such as A are short, alternating current impulses of considerable strength are produced in the toll line side of the toll switching trunk which often cause false operation of the alternating current relays in the composited circuit and especially are these impulses apt to cause false operation of the higher frequency relay 68. .By shortcircuiting both windings of the line side of the coil, however, during the flashing period this difficulty is entirely obviated.

When the subscriber at station A stops flashing. relay 10 operates over its previously traced circuit causing in turn the opera. tion of relay 22. Relay. 22, in operating, opens the circuit for the slow-to-release relay 13 which releases and also disconnects battery from the talking conductors of the cord circuit causing relay 16 to release and the 18 to be extinguished.

Upon completion of conversation and restoration of the receiver at the station A to the switchhook, relay 10 releases causing, in turn, the release of relay 22. Belay 22, in releasing, connects grounded battery to the cord circuit C causing relay 16 to operate and supervisory lamp 18 to be operated. The toll operator, noting the lighting of the lamp 18. removes the plug 15 from the ack 14;, thereby interrupting the circuit for relay 12 of the trunk circuit T. Belay 12, in releasing, completes a circuitthrough its normal contacts for lamp 7 at the B operators position indicating to the B operator that the toll operator has disconnected. The B opera-tor then removes the plug 2 from jack 1, whereupon all apparatus in the trunk circuit T is restored to normal.

If a call over the toll line originates with the subscriber A instead of from asubscriber having access to the distant end of the toll line L, the connection over the toll switching trunk Would be established in the same manner as previously described. The toll operator in such a case, however, would, before establishing the connection with the subsrriber at station A, call the toll operator at the distant exchange by inserting the plug 23 into the jack 24: and actuating the ringing key 88 associated with the cord circuit ating, causes the operation of relay 64c over an obvious circuit. Relay 64C, in operating, connects 135 cycle current at the source .65 to the conductors 81 and 82 of the toll line extending to the distant exchange, whereupon a relay at the distant office corresponding to relay 68 is actuated to release the slow-to-release relay corresponding to relay 66, which, in turn, causes the operation of the relay corresponding to relay 72, which, in operating, connects 16 cycle current to the toll line to actuate the drop 58. The operator at the distant exchange noting this signal inserts the plug 23 of the cord circuit G into jack 24 of the trunk circuit. The operation of the circuits at the distant office is identical with the operation of the circuits in the originating oflice and a description of the operation of the circuits when handling an outgoing call over the toll line is not deemed necessary.

hat is claimed is:

1. In a telephone system. a subscribers station, means including a trunk circuit. a cord circuit and a composited circuit for extending a connection therefrom or thereto, ringing current responsive means associated with said composited circuit, a signal in said cord circuit, means controlled the subscriber for flashing the signal in the cord circuit. and means responsive to said last means for preventing the operation of said ringing current responsive means during the flashing period.

2. In a telephone system, a subscribers station, means including a trunk circuit, a cord circuit and a composited circuit for extending a connection therefrom or thereto, a signal for said cord circuit, an alternating current relay in said composited circuit, a switchhook at the subscribers station, means responsive to actuations ot the switchhook tor flashing said signal, and means responsive to said last means for preventing the operation of the alternating current relay during the flashing period.

3. In a telephone system, a trunk circuit, an inductive device for dividing said trunlr circuit into first and second section, source of current tor each section, a supervisory relay associated with the second section, a relay in the first section in circuit with said source of current, means associated with the: trunl: circuit for interrupting the circuit of said rel, means controlled by said relay for tlashin said supervisory signal, and means also controlled by said relay tor short-circuitiug a portion or said inductive device during the dashing period.

4. In a telephone system, a circuit, a repeating coil inductively dividing said circuit into a first and a second section, a source of current for each section, supervisory signal associated with the second section, a relay in the first section in circuit with said source of current, means associated. with the circuit for interrupting the circuit of said relay to cause the energization and cleanergization thereof, means controlled by said relay for flashing said supervisory signal. and a slow-to-release relay also controlled by said relay tor short-circuiting a winding of said repeating coil.

5. In a telephone system, a suhscrihers station, a trunk circuit tor extending a con nection therefrom, repeating coil inductively dividing said trunlr circuit into inner and outer sections, a suhscrihers station connected to the inner sect-ion, cord circuit connected to the outer section, a composited circuit connected to the cord circuit, alternating current relays associated with said composite circuit. a signal for the cord circuit, source of current and a relay in series with the suhscrihers station. a switch at the suhscrihers station tor interrupting the flow of current through said relay, and means controlled by the relay for actuating said signal and for preventing the interruptions in the trunk circuit from causing the operation of the alternating current relays associated with the composited circuit.

6. In a telephone system, a circuit hav ing inner and outer sections, a repeating coil inductively uniting said sections, a signal associated with the outer section, a subscrihers set including a switch associated with the inner section, a source of current for the outer section, a relay to apply current from said source to cause theoperation of said signal, and means responsive to the actuation of the switch of said set for energizing said relay and for short-circuiting the windings of said repeating coil associated with the outer section of said circuit.

7. In a telephone system, a trunk circuit raving inner and outer sections, a repeatcoil inductively uniting said sections, a iggnal associated with the outer section, a suhscrihers set including a switchhool: associated with the inner section, a source of. current tor the outer section, a relay to apply current from said source to the outer section to cause the operationot said signal, means responsive to the actuation of the switch of said set for energizing said relay. and slow-to-release relay also controlled hy the switchhook of said set for short-circniting the windings of the repeating coil associated with the outer section of the trunk circuit.

8. A. telephone circuit comprising two sections, a repeating coil connecting said sections, a signal and a composited circuit associated with said sections, means for operating said signal, and means responsive to said last means for preventing false operation of said composited circuit while operating said signal.

9. A. toil switching trunk having two sections, an inductive device for connecting said sections, a signal and a composited circuit associated with said trunk, a switch and connections for operating said signal, and means actuated when signal ng for rendering said inductive device inetl'ective to produce false signals in said composited circuit.

ln witness whereof, I hereunto suhscrihe my name this 46th dav of May A. D. 1922.

LANGFORD J. BOlVNE, 

